Gadget Freak Case #232: Finding the Right Hydraulic Force

Ed Nauman found that using a hydraulic press to straighten a piece of material involved guesswork. You apply the force and then gradually increase it with each successive try. You usually track the appropriate force by counting the number of pulls on the pump handle. That's not very scientific.

Nauman created a gadget that indicates the actual force being applied. The goal was to make the process of using the hydraulic press quicker and more accurate.

Very professional looking. You used your mill to engrave the panel and added color. I never thought of using a mill to engrave a PCB. I have used the photo transfer stuff for prototypes, but programming your mill is so elegant. I personally think the orange wire is a nice touch ;-)

Actually, I made a modification similar to your proposal except I used a string pot instead of a caliper for more travel. I have found a number of uses for the press, since making these additions to it, that couldn't be done with a steam gage. I appreciate what you said about elegant solutions and all. I was a senior instrumentation engineer for Lockheed's Skunk Works Flight Test Division for 30 years. In Flight Test instrumentation, the job consists of an endless stream of unique measurement problems that require unique solutions. I like to think that most of mine were elegant.

I think the spirit of the Gadget Freak contest is in the interest of having fun rather than solving the world's toughest engineering chllenges. After all, most people would consider my Computer Controlled, Pneumatic actuated, Vacuum Assisted, Beer Can Crusher a hopelessley impractical, but fun creation. It sure makes people drink a lot of beer at my parties... :)

I do have a suggestion for an addition to your project that would make it a lot more fun. If you hook up a $20 digital caliper to your press to measure displacement, you would begin the makings of a "universal testing machine." Most digital calipers have a digital interface which can be readily interfaced with a PC (just Google it). If you then interface your pressure sensor with your PC, you can then have your PC display a stress versus strain graph displaying the elastic and plastic properties of your sample. It would also be very useful for getting your workpieces perfectly straight as you could read the displacement to the nearest thou.

I didn't realize the article was about having fun. Sorry, but try as I might, I don't see the fun in your solution. Is there something I'm missing?

I look at these sorts of articles as examples of an efficient engineering approach to a stated need. In my over 40 year engineering career, cost effectiveness has always been at the top of the list, both in cost and time. Elegant solutions is the name of the game, at least when it comes to public presentations. And believe me, working on a solution that's elegant is a great deal of fun, at least for me and our crew. It's the joy of engineering. The quicker and more efficiently you can finish a job, the quicker you can get on to the next challenging project. I especially like the projects that other people had given up on.

A caveman's wheel will not do the job of a car in most people's minds, while a mechanical gauge will do the job in measuring your hydraulic force.

If on the other hand the need is for automation, then an electronics approach is the way to go.

Boy, some people can take the fun out of anything... The caveman's wheel will still be around when your car is rusting in a junk pile or has been melted down for scrap. But I'll bet you don't drive the cave wheel.

The schematic was drawn in Sunstone's free design software "PCB123". Since their software is free, it limits the type of file outputs available to their native format. The schematic appears so poor because the only way to get an electronic copy is to do a screen capture and paste it into something that will allow saving to a different file type. Not the best way. If you go to Sunstone's website and download the program, I will send you the file so you can open it. I use PCB123 because it is a pretty good PCB design program and Sunstone's circuit board prices are reasonable. When I mill a board myself, I use PCB123 to draw the schematic and layout the board. But then I have to redraw it using my CADCAM program in order to get the tool paths. It is a tedious process, but for me, it beats spending $10K for PCB design software. And, for moderately populated boards, I can go from the first "back of the napkin" schematic to an assembled prototype in a day. Send me your email address and I will send you the schematic file and code listing.

enauman, What a nice analog and microcontroller application. I like the look of the front panel and I think it's impressive you made your pcbs by use of a milling operation. I definitely share this video with my Microprocessor & Microcontroller students at ITT Tech. Also, is there a clean circuit schematic diagram and software code available for this project?

While designing electronics has been a career for me, when it comes to spare time, I don't cannot envisage spending the time and effort to build such a device when simple $15 old fashion dial pressure gauges are readily available in a wide variety of full scale ranges.

To convert psi to pound force, you simple multiply the square inch area of your piston by the psi reading of the gauge. Let's say you have a hydraulic cylinder with a 1.5" bore (1.77 sq. inches) rated at 10 tons (20,00 pounds). The pressure at this rated load would be 11,299 psi. In the stated application, all you want is repeatability, so the actual units don't matter.

I've used a cheap 10,000 psi mechanical gauge on my press for over 30 years and it's still doing the job well. I can guarantee you that in 30 years your creation probably won't be in service and the parts used definitely won't be available, while commodity pressure gauges will still be available cheap. Such is the sad story of electronic devices.

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